Golf ball

ABSTRACT

A process for producing golf ball comprising a core and a cover layer, wherein the cover layer provides one or more deep dimples that extend through the cover layer and/or into a layer or component underneath is disclosed. The cover may be a single layer or it may include multiple layers. If the cover is a multi-layer cover, the dimples extend to or into at least the first inner cover layer, and may extend into two or more inner cover layers. If the cover is a single layer, the dimples extend into the core. The dimples may be spherical or non-spherical, and the portion of the dimple that extends to or into the next inner layer may be the same or different shape as the outer portion of the dimple.

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] The present application claims priority upon U.S. ProvisionalApplication Serial No. 60/337,123, filed Dec. 4, 2001; U.S. ProvisionalApplication Serial No. 60/356,400, filed Feb. 11, 2002; and U.S.Provisional Application Serial No. 60/422,426, filed Oct. 30, 2002.

FIELD OF THE INVENTION

[0002] The present invention relates to a method of forming golf balls,and more particularly to a process for producing golf balls having oneor more deep dimples that extend through the outer cover layer to and/orinto one or more layers or components thereunder.

BACKGROUND OF THE INVENTION

[0003] A number of one-piece, two-piece (a solid resilient center orcore with a molded cover), and multi-layer (liquid or solid center andmultiple mantle and/or cover layers) golf balls have been produced.Different types of materials and/or processing parameters have beenutilized to formulate the cores, mantles, covers, etc. of these balls,which dramatically alter the balls' overall characteristics.

[0004] For certain applications it is desirable to produce a golf ballhaving a very thin cover layer. However, due to equipment limitations,it is often very difficult to mold a thin cover. Accordingly, it wouldbe beneficial to provide a technique for producing a relatively thinouter cover layer.

[0005] Moreover, retractable pins have been utilized to hold, or center,the core or core and mantle and/or cover layer(s) in place while moldingan outer cover layer (or potentially other layers) thereon. These pinsare retracted during the latter stages of the molding process with thestill somewhat fluid cover or mantle material filling the void left bythe pins.

[0006] The retractable pins, however, sometimes produce centeringdifficulties and cosmetic problems (i.e. pin flash, pin marks, etc.) inthe lands or dimples during retraction, which in turn require additionalhandling to produce a golf ball suitable for use and sale. Additionally,the lower the viscosity of the mantle and/or cover materials, thegreater the tendency for the retractable pins to stick due to materialaccumulation, making it necessary to shut down and clean the moldsroutinely. Furthermore, the pins also produce a “cold weld” when theirvoids are filled during molding. This is deleterious to durability asthe cover may fail by cracking through the filled pin voids after manyhits.

[0007] Accordingly, it would also be desirable to provide a method forforming a thin outer cover layer or intermediate layer on a golf ballwithout the use of retractable pins.

SUMMARY OF THE INVENTION

[0008] In one aspect, the present invention is directed to a process forproducing a golf ball having dimples in an outer cover layer that extendto, and/or into at least the next inner layer or core of the ball.

[0009] A further aspect of the invention is to provide a golf ballhaving a dimpled cover that is thinner than traditional cover layerswith one or more dimples.

[0010] The present invention provides, in another aspect, a process forforming a golf ball having a plurality of deep dimples by providing anintermediate ball comprising at least a core. A molding apparatus isalso provided having a generally spherical molding chamber with amolding surface defined by (i) a first plurality of raised regions forforming a plurality of dimples on the cover layer, and (ii) a secondplurality of raised regions. Each of the second plurality of raisedregions extends beyond the first plurality of raised regions, forconcentrically positioning an object within the molding chamber and forforming deep dimples. The molding apparatus also includes an assemblyfor administering a flowable material into the molding chamber. Theprocess also comprises a step of providing to the molding apparatus, aflowable material suitable for use as the cover layer for the golf ball.The process also includes a step of positioning the intermediate ballwithin the molding chamber such that the second plurality of raisedregions of the molding surface contacts and retains the intermediateball within the molding chamber. The process also includes a step ofadministering the flowable material into the molding chamber andgenerally between the intermediate ball and the molding surface. Theprocess also comprises a step of upon curing, removing the molded ballfrom the molding apparatus.

[0011] The present invention also provides, in another aspect, a processfor forming a cover layer having a plurality of deep dimples on a golfball core. The process comprises the steps of providing a golf ball coreand providing a flowable material for forming the layer on the golf ballcore. The process also includes a step of providing a mold including (i)a generally spherical molding chamber having an outer surface includinga plurality of raised protrusions that form a plurality of deep dimplesin the layer, and (ii) provisions for introducing the flowable materialinto the molding chamber. The process also includes a step ofconcentrically positioning the golf ball core in the molding chambersuch that the plurality of raised protrusions contact the golf ballcore. The process also includes a step of introducing the flowablematerial into the molding chamber such that the material flows betweenthe golf ball core and the outer surface of the molding chamber tothereby form the layer.

[0012] In yet a further aspect, the present invention provides a processfor forming a golf ball having at least one dimple that extends throughan outer layer of the ball. The process comprises a step of providing anintermediate golf ball assembly comprising at least a core. The processalso includes a step of providing a molding apparatus including agenerally spherical molding chamber having a first population of raisedregions for forming a plurality of dimples on an outer layer of the golfball, and at least one other raised region having a height that isgreater than the thickness of the outer layer. The process furtherincludes a step of positioning the intermediate golf ball assembly inthe molding chamber. The process also includes a step of administering aflowable material adapted to form the outer layer, to the moldingapparatus.

[0013] The invention accordingly comprises several compositions,components and steps and the relation of one or more of suchcompositions, components and steps with respect to each other. Moreover,the invention is directed to articles possessing the features,properties, and the relation of elements exemplified in the followingdetailed disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following is a brief description of the drawings, which arepresented for the purposes of illustrating the present invention and notfor the purposes of limiting the same.

[0015]FIG. 1 is a cross-sectional view of a preferred embodiment golfball according to the present invention having a core and a single coverlayer having dimples, wherein one or more of the dimples extends throughthe cover to and/or into the underlying core;

[0016]FIG. 2 is a diametrical cross-sectional view of the preferredembodiment golf ball illustrated in FIG. 1;

[0017]FIG. 3 is a cross-sectional view of another preferred embodimentgolf ball according to the present invention having a core component anda cover component, wherein the cover component includes an inner coverlayer and an outer cover layer having dimples formed therein, andwherein one or more of the dimples of the outer cover layer extends toand/or into the underlying inner cover layer;

[0018]FIG. 4 is a diametrical cross-sectional view of the preferredembodiment golf ball illustrated in FIG. 3;

[0019]FIG. 5 is a cross-sectional detail view of a portion of apreferred embodiment golf ball according to the present invention havinga core and a cover illustrating a dual radius dimple that extendsthrough the cover into the underlying core;

[0020]FIG. 6 is a cross-sectional detail view of a portion of apreferred embodiment golf ball according to the present invention havinga core and a cover illustrating a dual radius dimple that extendsthrough the outer cover layer to the outer surface of the core;

[0021]FIG. 7 is a cross-sectional detail view of a portion of apreferred embodiment golf ball according to the present invention havinga core, an inner cover layer, and an outer cover layer, wherein theouter cover layer has a dual radius dimple that extends into the innercover layer;

[0022]FIG. 8 is a cross-sectional detail view of a portion of apreferred embodiment golf ball according to the present invention havinga core, an inner cover layer, and an outer cover layer illustrating adual radius dimple that extends through the outer cover layer to theinner cover layer of the ball;

[0023]FIG. 9 is a top view of a preferred embodiment golf ball accordingto the present invention having a first population of typical dimplesalong with three deeper dimples configured in a triangular pattern aboutthe pole of the ball;

[0024]FIG. 10 is a top view of a preferred embodiment golf ballaccording to the present invention having a first population of typicaldimples along with four deeper dimples arranged in a diamond patternabout the pole of the ball;

[0025]FIG. 11 is a cross-sectional detail view of a portion of apreferred embodiment golf ball according to the present invention havinga core, an inner cover or mantle layer, and an outer cover layerillustrating a dimple that extends through the outer cover layer to themantle layer;

[0026]FIG. 12 is a top view of a portion of a preferred embodiment golfball according to the present invention having a cover with dimplesformed in two layers of the cover and illustrating an inner dimpleportion formed in the inner cover layer and an outer dimple portionformed in the outer cover layer;

[0027]FIG. 13 is a graph illustrating the relationship between thelocation on a golf ball of certain dimples according to the inventionand the resulting forces in a self-supporting cavity during molding;

[0028]FIG. 14 is a perspective view of a golf ball illustrating a regiondefined along the outer surface of the ball; and

[0029]FIG. 15 is a schematic view of a preferred embodiment moldingassembly and a golf ball core according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present invention relates to improved golf balls,particularly a golf ball comprising a cover having one or more layersdisposed about a core. The cover has one or more, preferably a pluralityof, deep dimples or apertures that extend through the outer cover toand/or into, or through, one or more layers underneath. The core can bea wound, liquid, hollow, metal or a solid core, or the like, with asolid core being the more preferred. The golf balls of the presentinvention, which can be of a standard or enlarged size, have a uniquecombination of cover layer thicknesses and dimple configuration.

[0031] As explained in greater detail herein, the present invention alsorelates to the use of one or more “deep dimples.” These deep dimpleshave depths greater than other dimples on a ball. Such deep dimplesextend through at least one cover layer to, and/or into, the underlyingsurface, component or layer of the ball.

[0032] With regard to dimple configuration or cross-sectional geometry,the present invention is based upon the identification of variousparticularly preferred characteristics as follows. Typically, forcircular dimples, dimple diameter is used in characterizing dimple sizerather than dimple circumference. The diameter of typical dimples mayrange from about 0.050 inches to about 0.250 inches. A preferreddiameter of a typical dimple is about 0.150 inches. The deep dimples mayhave these same dimensions or may have dimensions as described ingreater detail herein. As will be appreciated, circumference of a dimplecan be calculated by multiplying the diameter times π.

[0033] The depth of typical dimples previously utilized in the trade mayrange from about 0.002 inches to about 0.020 inches or more dependingupon the cover thickness and/or flight characteristics desired. A depthof about 0.010 inches is typical for conventional dimples. These dimplesare utilized on golf balls having typical outer cover thicknesses of0.030 to 0.100 inches.

[0034] However, the depth of a deep dimple of the present invention asdescribed herein is greater than the depth of a typical or conventionaldimple. Preferably, the deep dimples extend through at least the outercover layer of the ball. More preferably, the deep dimples have a depththat is deeper than the depth of the typical dimples by at least 0.002inches.

[0035] In this regard, in a traditional prior art ball, the dimpledepth, which is generally about 0.010 inches, is generally less than thethickness of the cover so that the dimple does not touch or extend tothe next layer or even come close to the next layer. Therefore, there isa minimum cover thickness that can be used in order to have dimples ofthe desired depth. The golf ball of the present invention eliminates theneed to have a cover thickness greater than the desired dimple depthbecause one or more layers can make up the dimple, and thus, each layermay be very thin (less than 0.010 inches).

[0036] Specifically, depth of a dimple may be defined in at least twofashions. A first approach is to extend a chord from one side of adimple to another side and then measure the maximum distance from thatchord to the bottom of the dimple. This is referred to herein as a“chordal depth.” Alternatively, another approach is to extend animaginary line corresponding to the curvature of the outer surface ofthe ball over the dimple whose depth is to be measured. Then, thedistance from that imaginary line to a bottom most point in the dimpleis measured. This is referred to herein as a “periphery depth.” Thelatter format of dimple depth determination is used herein unless notedotherwise.

[0037] As described in more detail below, the deep dimples included inthe present invention are particularly useful when molding certainlayers or components about cores or intermediate ball assemblies. Thedepth (i.e. periphery depth) of a deep dimple as described herein mayrange from about 0.002 inches to about 0.140 inches, more preferablyfrom about 0.002 inches to about 0.050 inches, and more preferably fromabout 0.005 inches to about 0.040 inches. Preferably, a total depth ofabout 0.025 inches is desired. The depth of a deep dimple as describedherein is greater than the depth of a typical dimple, and extends to atleast the outermost region of the mantle or core. Alternatively, thedeep dimples preferably extend to the bottom of a matched set of dimpleson the mantle or the core. Generally, depth is given with respect toperiphery depth from the outer surface of a finished ball, unless statedotherwise.

[0038] The diameter of the deep dimples may be dissimilar, butpreferably is the same as other dimples on a ball, and may range fromabout 0.025 inches to about 0.250 inches and more preferably from about0.050 inches to about 0.200 inches. A preferred diameter is about 0.150inches.

[0039] In one embodiment, the present invention relates to a golf ballcomprising a core and a cover layer, wherein the cover layer providesdimples including one or more deep dimples that extend into or throughthe next inner layer or component. The cover may be a single layer ormay comprise multiple layers, such as two, three, four, five or morelayers and the like. If the cover is a multi-layer cover, the dimplesextend to or into at least the first inner cover layer, and may extendinto or through a further inner cover layer, a mantle or intermediatelayer, and/or the core. If the cover is a single layer, the deep dimplesmay extend into or through a mantle layer to the core. The coverlayer(s) may be formed from any material suitable for use as a cover,including, but not limited to, ionomers, non-ionomers and blends ofionomers and non-ionomers.

[0040] In another embodiment, the present invention relates to a golfball comprising a core and a cover layer, wherein the cover layerprovides dimples that extend to the outer surface of the core. The golfball may optionally comprise a thin barrier coating between the core andthe cover that limits the transition of moisture to the core. Thebarrier coating is preferably at least about 0.0001 inches thick.Preferably, the barrier layer is at least 0.003 inches thick. In atwo-piece golf ball, a barrier coating is preferably provided betweenthe core and the cover.

[0041] In a further embodiment, the present invention relates to a golfball having a plurality of dimples along its outer surface. Inaccordance with the present invention, one or more of these dimples,preferably two or more of the dimples, and more preferably three or moreof the dimples, are deep dimples that extend entirely through the coverlayer of the ball, and into one or more underlying components or layersof the ball. For instance, for a golf ball comprising a core and a coverlayer disposed about the core, the deep dimples preferably extendthrough the cover layer and into the core.

[0042] Additionally, the core or mantle layer may be “dimpled” such thatthe dimples on the core or mantle match up with and accept the “deep”dimples from the mold. If one or more layers such as an intermediatemantle layer are provided between the core and the cover layer, the deepdimples preferably extend through the cover layer and into and/orthrough one or more of those layers. The deep dimples may additionallyextend into the core.

[0043] The deep dimples of the present invention may be spherical ornon-spherical. Additionally, the portion of the deep dimple that extendsto, or into the next inner layer or component may be the same ordifferent size and/or shape as the outer portion of the dimple.

[0044] Moreover, the deep dimples of the present invention can also beutilized to enhance treatment (i.e., deburring, painting, printing,etc.) of the molded ball. For example, the deep dimple can be utilizedto hold or fix the molded ball for surface modifications and/or coating.

[0045]FIGS. 1 and 2 illustrate a preferred embodiment golf ball inaccordance with the present invention. Specifically, FIGS. 1 and 2illustrate a golf ball 10 comprising a core 20 having a cover layer 30formed about the core. The cover layer 30 defines a plurality of dimples40 along its outer surface 35. One or more of the dimples, andpreferably two or more of the dimples, extend into the core 20 disposedunderneath the cover layer 30. These dimples are herein referred to asdeep dimples and shown in the figures as dimples 42.

[0046]FIGS. 3 and 4 illustrate another preferred embodiment golf ball110 in accordance with the present invention. The golf ball 110comprises a core 120 having an inner cover layer 150 disposed thereonand an outer cover layer 160 formed about the inner cover layer 150. Thecover layers 160 and 150 define a plurality of dimples 140 along theouter surface of the outer cover layer 160. One or more of the dimples,and preferably two or more of the dimples, and more preferably three ormore of the dimples per hemisphere, extend entirely through the outercover layer 160 and at least partially into the inner cover layer 150.These dimples, which extend through the outer cover layer, are againreferred to herein as deep dimples and shown in the figures as dimples142.

[0047]FIG. 11 illustrates a partial cross section of a golf ball 810defining a deep dimple 850 formed in an outer cover layer 820 disposedon a mantle (or inner cover) layer 830 that in turn is disposed on acore 840. The deep dimple 850 has a common curvature. Alternatively, thedeep dimples may be defined by regions of different curvature or shape.This is described in greater detail below.

[0048] The deep dimples can be circular, non-circular, a combination ofcircular and non-circular, or any other shape desired. They may be ofthe same or differing shape, such as a circular larger dimple having anoval smaller dimple within the circular dimple, or an oval larger dimplehaving a circular or other shape within the larger dimple. The dimplesdo not have to be symmetrical.

[0049] Providing deep dimples formed in multiple layers allows thedimple depth to be spread over two or more layers. FIG. 12 illustratesdimples 940 formed in both the inner cover layer and the outer coverlayer. The inner portion of the dimple 946 is formed in the inner coverlayer, and the outer portion of the dimple 948 is formed in the outercover layer. For a two-piece ball, dimples may be formed in the core andthe single cover layer in the same way as previously described.Additionally, dimples may be formed in more than two cover and/or corelayers if desired.

[0050] In another preferred embodiment, a multi-layer golf ball isproduced that has one or more deep dimples that protrude into the ballthrough at least one layer, such as an outer cover layer. In a furtherpreferred embodiment, the deep dimple protrudes through at least twolayers. The dimples of the at least two layers are configured with thesame geometric coordinates (that is, the approximate center of bothdimples would be in the same location, and so the dimples are concentricwith respect to each other), producing a golf ball having a dimpledlayer over a dimpled layer. This allows for much thinner layers withtraditional dimples. The dimples of one or more inner layers may be ofvarying depths, diameters and radii, yet still aligned with the dimplesof the outer layer. This also allows for a dimple within a dimple, wherethere is a smaller dimple in at least one inner or mantle layer that iswithin a larger diameter dimple in the outer layer, such as the dimplesshown in FIGS. 5 to 8.

[0051] FIGS. 5 to 8 illustrate a deep dimple that is a dual radiusdimple, a dual region dimple, or a dimple within a dimple (these termsare generally used interchangeably herein). One advantage of a dualradius dimple is that the deeper part of the dual radius may be filledin with a coating or other material. This provides an effective methodfor forming dimple depths to a desired value as compared to othermethods of dimple formation. The dimple shape may be any shape desired,and each dimple may be the same or different shape. The shape of adimple or region thereof is given when viewed in a direction extendingalong a diameter of the golf ball. The respective regions of the dualregion dimples may be in a variety of different (or the same) shapessuch as circular, elliptical, oval, square, triangular, and polygonal.

[0052] Preferably, the depth of the second or deepest portion of thedual radius dimple may be expressed as a percentage of the total depthof the dimple. Specifically, the region or portion of the dimple thatextends to the outermost surface of the ball may be referred to hereinas the “major” dimple. And, likewise, the portion of the dimple thatextends to the deepest portion or depth of the dimple can be referred toherein as the “minor” dimple. Accordingly, the preferred depth of themajor dimple is approximately from about 40% to about 80% of the overalldimple depth. Accordingly, the preferred depth of the minor dimple isapproximately 20% to about 60% of the overall dimple depth. The depth ismeasured from the chord of the major dimple extending between the majorand minor portions to the bottom of the minor dimple. As explained ingreater detail herein, this is the “chordal depth” since this depth istaken with regard to a chord extending across a span of the dimple. Withregard to diameters, the preferred diameter of the minor dimple is fromabout 10% to about 70% of the diameter of the major dimple.

[0053]FIG. 5 is a cross-sectional detail illustrating a portion of apreferred embodiment golf ball in accordance with the present invention.This preferred embodiment golf ball 210 comprises a core 220 having acover layer 230 formed thereon. The cover layer defines at least onedeep dimple 240 along its outer surface 235. As described in conjunctionwith FIGS. 1 and 2, it is preferred that one or more (preferably two ormore, more preferably three or more per hemisphere) of the dimplesextends entirely through the cover layer and into the core disposedunderneath the cover layer.

[0054]FIG. 5 further illustrates a deep dimple defined by two differentcurvatures. Referring to FIG. 5, a first radius R₁ defines the portionof the dimple from the outer surface 235 of the golf ball 210 to a pointat which the deep dimple extends into a layer underneath the coverlayer. At this point, the curvature of the dimple changes and is definedby radius R₂.

[0055] Preferably, R₁, is from about 0.130 inches to about 0.190 inches,and most preferably, R₁, is from about 0.140 to about 0.180 inches. Forsome embodiments, R₁ ranges from about 0.100 inches to about 1.000 inch,and most preferably from about 0.200 inches to about 0.800 inches.

[0056] Preferably, R₂ is from about 0.025 inches to about 0.075 inches,and most preferably, R₂ is about 0.050 to about 0.065 inches. For someembodiments, R₂ ranges from about 0.002 inches to about 0.50 inches, andmost preferably from about 0.010 inches to about 0.200 inches.

[0057] The overall diameter or span, generally referred to as the “majorchordal diameter,” of the dimple 240 is designated herein as D₁. Thediameter or span, generally referred to as the “minor chordal diameter,”of the portion of the dimple that extends into the layer underneath theouter cover layer is designated herein as D₂.

[0058] Preferably, D₁ is from about 0.030 inches to about 0.250 inches,more preferably from about 0.100 inches to about 0.186 inches, and mostpreferably, D₁ is about 0.146 inches to about 0.168 inches. For someembodiments, D₁ ranges from about 0.100 inches to about 0.250 inches,and most preferably D₁ is about 0.140 inches to about 0.180 inches.

[0059] Preferably D₂ is from about 0.020 inches to about 0.160 inches,more preferably from about 0.030 inches to about 0.080 inches, and mostpreferably, D₂ is about 0.056 inches. For some embodiments, D₂ is fromabout 0.040 inches to about 0.060 inches.

[0060] Accordingly, the overall depth of the deep dimple portion that isdefined by R₁ is designated herein as H₁ and the depth or portion of thedimple that is defined by R₂ is designated herein as H₂. Preferably, H₁is from about 0.005 inches to about 0.135 inches, more preferably fromabout 0.005 to about 0.025 inches, more preferably from about 0.010inches to about 0.015 inches, and most preferably, H₁ is about 0.015inches. For some embodiments, H₁ is from about 0.005 inches to about0.015 inches. H₂ may range from about 0.005 inches to about 0.135inches, and more preferably from about 0.005 to about 0.050 inches.Preferably, H₂ ranges from about 0.005 inches to about 0.030 inches andis about 0.010 inches. For some embodiments, H₂ is from about 0.005inches to about 0.015 inches.

[0061] Referring to FIG. 6, another preferred embodiment golf ball 310is illustrated. In this version of the present invention, a golf ball310 comprises a core 320 and a cover layer 330 formed thereon. The coverlayer 330 defines at one deep dimple 340 along the outer surface 335 ofthe golf ball 310. As can be seen, the dimple 340 is defined by twodifferent curvatures, each of which is defined by radii R₂ and R₁ aspreviously described with respect to FIG. 5. The other parameters D₁,D₂, H₁, and H₂ are as described with respect to FIG. 5. FIG. 6illustrates an embodiment in which the dimple 340 extends to the core320 and not significantly into the core. In contrast, the versionillustrated in FIG. 5 is directed to a dimple configuration in which adimple extends significantly into the underlying core.

[0062]FIG. 7 illustrates a preferred embodiment golf ball 410 comprisinga core 420, a mantle or inner cover layer 450, and an outer cover layer460. The outer cover layer 460 defines at least one deep dimple 440along the outer surface 435 of the ball 410. The dimple 440 is definedby two different regions or two curvatures, each of which is in turndefined by radii R₂ and R₁. The other parameters D₁, D₂, H₁, and H₂ areas described with respect to FIG. 5. As can be seen in FIG. 7, thedimple 440 extends entirely through the outer cover layer 460 and intothe inner cover layer or mantle layer 450.

[0063]FIG. 8 illustrates another preferred embodiment golf ball 510 inaccordance with the present invention. The golf ball 510 comprises acore 520 having disposed thereon an inner cover layer or mantle layer550 and an outer cover layer 560. Defined along the perimeter or outerperiphery of the ball 510 is at least one deep dimple 540. The dimple540 is defined along the outer surface 535 of the ball 510. The dimple540 has two different regions or curvatures each defined by radii R₂ andR₁, as previously described. The other parameters D₁, D₂, H₁, and H₂ areas described with respect to FIG. 5. The version illustrated in FIG. 8reveals a dimple 540 that does not significantly extend into the mantlelayer or inner cover layer 550. Instead, the dimple 540 only extends tothe outermost region of the mantle layer or inner cover layer 550.

[0064] In the various dual-radius dimples, dual region dimples, ordimples-within-dimples described herein, the present invention includesfilling either or both of the regions with various materials. The fillermaterials are preferably different than cover materials, but may includesuch. Preferably, the filler materials incorporate one or more coloringagents.

[0065] An important characteristic of dimple configuration is the volumeratio. The volume ratio is the sum of the volume of all dimples takenbelow a chord extending across the top of a dimple, divided by the totalvolume of the ball.

[0066] The volume ratio is a critical parameter for ball flight. A highvolume ratio generally results in a low flying ball. And a low volumeratio often results in a high-flying ball. A preferred volume ratio isabout 1%. The balls of the present invention however may be configuredwith greater or lesser volume ratios.

[0067] The number and/or layout of dimples will not necessarily changethe coverage, i.e. surface area. A typical coverage for a ball of thepresent invention is about 60% to about 95% and preferably about 83.8%.In other embodiments, this preferred coverage is about 84% to about 85%.These percentages are the percent of surface area of the ball occupiedby dimples. It will be appreciated that the present invention golf ballsmay exhibit coverages greater or less than that amount.

[0068] For configurations utilizing dimples having two or more regionsof different curvature, i.e. dimple within a dimple, there is lessimpact on the volume ratio than the use of deep dimples. If there areenough of either dimples within dimples or deep dimples, that willeventually impact the aerodynamics of the ball will eventually beimpacted.

[0069] The optimum or preferred number of deep dimples utilized per ballvaries. The preferred number is the amount necessary to secure or centerthe core during molding without adversely affecting the aerodynamics ofthe finished ball. However, the present invention includes the use of arelatively large number of deep dimples. That is, although most of thefocus of the present invention is directed to the use of only a few deepdimples per golf ball, i.e. from 1 to 10, preferably 1 to 8, morepreferably 1 to 6, the invention includes the use of a significantlygreater number such as from about 50 to about 250. It is alsocontemplated that for some applications, it may be desirable to formall, or nearly all, dimples on a golf ball as deep dimples, such as forexample, from about 50 to about 500.

[0070] In general, as dimples are made deeper, the ball will fly loweras compared to the use of dimples that are shallower. As the number ofdeep dimples increases, the ball will exhibit a lower flight trajectory.Accordingly, the preferred approach is to utilize a smaller or fewernumber of deep dimples. However, for other applications, the presentinvention includes a ball with many deep dimples.

[0071] During molding, deep dimples can impregnate the core or mantle.Generally, the deep dimples will extend into the core from the moldingcavity and contact the core. But, the core will rebound back to itsoriginal shape to some extent so that the volume of the dimple at thepoint of contact is less than would otherwise be expected. This isexplained in greater detail below.

[0072] The overall shape of the dimples, including deep dimples, may benearly any shape. For example, shapes such as hexagon, pentagon,triangle, ellipse, circle, etc. are all suitable. There is no limit tothe number of shapes, although some shapes are preferred over others. Atpresent, circular dimples are preferred. As for the cross-sectionalconfiguration, the dimples may utilize any geometry. For instance,dimples may be defined by a constant curve or a multiple curvature ordual radius configuration or an elliptical or teardrop shaped region.

[0073] Cover Layer(s)

[0074] The cover comprises at least one layer. For a multi-layer cover,the cover comprises at least two layers, and it may comprise any numberof layers desired, such as two, three, four, five, six and the like. Atwo-piece cover comprises a first or inner layer or ply (also referredto as a mantle layer) and a second or outer layer or ply.

[0075] The inner layer can be ionomer, ionomer blends, non-ionomer,non-ionomer blends, or blends of ionomer and non-ionomer. The outerlayer can be ionomer, ionomer blends, non-ionomer, non-ionomer blends,or blends of ionomer and non-ionomer, and may be of the same ordifferent material as the inner cover layer. For multi-layer covershaving three or more layers, each layer can be ionomer, non-ionomer, orblends thereof, and the layers may be of the same or differentmaterials.

[0076] In another preferred embodiment of a golf ball, the inner layeror single cover layer is comprised of a high acid (i.e. greater than 16weight percent acid) ionomer resin or high acid ionomer blend. Morepreferably, the inner layer is comprised of a blend of two or more highacid (i.e. greater than 16 weight percent acid) ionomer resinsneutralized to various extents by different metal cations. The innercover layer may or may not include a metal stearate (e.g., zincstearate) or other metal fatty acid salt. The purpose of the metalstearate or other metal fatty acid salt is to lower the cost ofproduction without affecting the overall performance of the finishedgolf ball.

[0077] In a further embodiment, the inner layer or single cover layer iscomprised of a low acid (i.e. 16 weight percent acid or less) ionomerresin or low acid ionomer blend. Preferably, the inner layer or singlelayer is comprised of a blend of two or more low acid (i.e. 16 weightpercent acid or less) ionomer resins neutralized to various extents bydifferent metal cations. As with the high acid inner cover layerembodied, the inner cover layer may or may not include a metal stearate(e.g., zinc stearate) or other metal fatty acid salt.

[0078] In golf balls having a multi-layer cover, it has been found thata hard inner layer(s) and/or low driver spin provides for a substantialincrease in resilience (i.e., enhanced distance) over known multi-layercovered balls. A softer outer layer (or layers) provides for desirable“feel” and high spin rate while maintaining respectable resiliency. Thesoft outer layer allows the cover to deform more during impact andincreases the area of contact between the club face and the cover,thereby imparting more spin on the ball. As a result, the soft coverprovides the ball with a balata-like feel and playabilitycharacteristics with improved distance and durability. Consequently, theoverall combination of the inner and outer cover layers results in agolf ball having enhanced resilience (improved travel distance) anddurability (i.e. cut resistance, etc.) characteristics while maintainingand in many instances, improving, the playability properties of theball.

[0079] The combination of a hard inner cover layer with a soft outercover layer provides for excellent overall coefficient of restitution(for example, excellent resilience) because of the improved resiliencyproduced by the inner cover layer. While some improvement in resiliencyis also produced by the outer cover layer, the outer cover layergenerally provides for a more desirable feel and high spin, particularlyat lower swing speeds with highly lofted clubs such as half wedge shots.

[0080] In one preferred embodiment, the inner cover layer may be harderthan the outer cover layer and generally has a thickness in the range of0.0005 to 0.15 inches, preferably 0.001 to 0.10 inches for a 1.68 inchball, and sometimes slightly thicker for a 1.72 inch (or more) ball. Thecore and inner cover layer (if applicable) together preferably form aninner or intermediate ball having a coefficient of restitution of 0.780or more and more preferably 0.790 or more, and a diameter in the rangeof 1.48 to 1.66 inches for a 1.68 inch ball and 1.50 to 1.70 inches fora 1.72 inch (or more) ball.

[0081] The inner cover layer preferably has a Shore D hardness of 60 ormore (or at least 90 Shore C). It is particularly advantageous if thegolf balls of the invention have an inner layer with a Shore D hardnessof 65 or more (or at least 100 Shore C). These measurements are made ingeneral accordance to ASTM 2240 except that they are made on the ballitself and not on a plaque. If the inner layer is too soft or thin, itis sometimes difficult to measure the Shore D of the inner layer as thelayer may puncture during measurement. In such circumstances, analternative Shore C measurement should be utilized. Additionally, if thecore (or inner layer) is harder than the layer being measured, this willsometimes influence the reading.

[0082] Moreover, if the Shore C or Shore D is measured on a plaque ofmaterial, different values than those measured on the ball will result.Consequently, when a Shore hardness measurement is referenced to herein,it is based on a measurement made on the ball, except if specificreference is made to plaque measurements.

[0083] The above-described characteristics of the inner cover layerprovide an inner ball having a PGA compression of 100 or less. It isfound that when the inner ball has a PGA compression of 90 or less,excellent playability results.

[0084] The inner layer compositions of the embodiments described hereinmay include the high acid ionomers such as those developed by E.I.DuPont de Nemours & Company under the trademark Surlyn® and by ExxonCorporation under the trademarks Escor® or lotek®, or blends thereof.Examples of compositions which may be used as the inner layer herein areset forth in detail in U.S. Pat. No. 5,688,869, which is incorporatedherein by reference. Of course, the inner layer high acid ionomercompositions are not limited in any way to those compositions set forthin said patent. Those compositions are incorporated herein by way ofexamples only.

[0085] The high acid ionomers which may be suitable for use informulating the inner layer compositions are ionic copolymers which arethe metal (such as sodium, zinc, magnesium, etc.) salts of the reactionproduct of an olefin having from about 2 to 8 carbon atoms and anunsaturated monocarboxylic acid having from about 3 to 8 carbon atoms.Preferably, the ionomeric resins are copolymers of ethylene and eitheracrylic or methacrylic acid. In some circumstances, an additionalcomonomer such as an acrylate ester (for example, iso- orn-butylacrylate, etc.) can also be included to produce a softerterpolymer. The carboxylic acid groups of the copolymer are partiallyneutralized (for example, approximately 10-100%, preferably 30-70%) bythe metal ions. Each of the high acid ionomer resins which may beincluded in the inner layer cover compositions of the invention containsgreater than 16% by weight of a carboxylic acid, preferably from about17% to about 25% by weight of a carboxylic acid, more preferably fromabout 18.5% to about 21.5% by weight of a carboxylic acid.

[0086] The high acid ionomeric resins available from Exxon under thedesignation Escor® or lotek®, are somewhat similar to the high acidionomeric resins available under the Surlyn® trademark. However, sincethe Escor®/lotek® ionomeric resins are sodium, zinc, etc. salts ofpoly(ethylene-acrylic acid) and the Surlyn® resins are zinc, sodium,magnesium, etc. salts of poly(ethylene-methacrylic acid), distinctdifferences in properties exist. It is also contemplated to utilizecommercially available resins that have been modified withethylene/acrylic acid resins for example.

[0087] Examples of the high acid methacrylic acid based ionomers foundsuitable for use in accordance with this invention include, but are notlimited to, Surlyn® 8220 and 8240 (both formerly known as forms ofSurlyn® AD-8422), Surlyn® 9220 (zinc cation), Surlyn® SEP-503-1 (zinccation), and Surlyn® SEP-503-2 (magnesium cation). According to DuPont,all of these ionomers contain from about 18.5 to about 21.5% by weightmethacrylic acid.

[0088] Examples of the high acid acrylic acid based ionomers suitablefor use in the present invention also include, but are not limited to,the Escor® or lotek® high acid ethylene acrylic acid ionomers producedby Exxon such as Ex 1001, 1002, 959, 960, 989, 990, 1003, 1004, 993, and994. In this regard, Escor® or lotek® 959 is a sodium ion neutralizedethylene-acrylic neutralized ethylene-acrylic acid copolymer. Accordingto Exxon, loteks® 959 and 960 contain from about 19.0 to about 21.0% byweight acrylic acid with approximately 30 to about 70 percent of theacid groups neutralized with sodium and zinc ions, respectively.

[0089] Furthermore, as a result of the previous development by theassignee of this application of a number of high acid ionomersneutralized to various extents by several different types of metalcations, such as by manganese, lithium, potassium, calcium and nickelcations, several high acid ionomers and/or high acid ionomer blendsbesides sodium, zinc and magnesium high acid ionomers or ionomer blendsare also available for golf ball cover production. It has been foundthat these additional cation neutralized high acid ionomer blendsproduce inner cover layer compositions exhibiting enhanced hardness andresilience due to synergies which occur during processing. Consequently,these metal cation neutralized high acid ionomer resins can be blendedto produce substantially higher C.O.R.'s than those produced by the lowacid ionomer inner cover compositions presently commercially available.

[0090] More particularly, several metal cation neutralized high acidionomer resins have been produced by the assignee of this invention byneutralizing, to various extents, high acid copolymers of analpha-olefin and an alpha, beta-unsaturated carboxylic acid with a widevariety of different metal cation salts. This discovery is the subjectmatter of U.S. Pat. No. 5,688,869, incorporated herein by reference. Ithas been found that numerous metal cation neutralized high acid ionomerresins can be obtained by reacting a high acid copolymer (i.e. acopolymer containing greater than 16% by weight acid, preferably fromabout 17 to about 25 weight percent acid, and more preferably about 20weight percent acid), with a metal cation salt capable of ionizing orneutralizing the copolymer to the extent desired (for example, fromabout 10% to 90%).

[0091] The base copolymer is made up of greater than 16% by weight of analpha, beta-unsaturated carboxylic acid and an alpha-olefin. Optionally,a softening comonomer can be included in the copolymer. Generally, thealpha-olefin has from 2 to 10 carbon atoms and is preferably ethylene,and the unsaturated carboxylic acid is a carboxylic acid having fromabout 3 to 8 carbons. Examples of such acids include acrylic acid,methacrylic acid, ethacrylic acid, chloroacrylic acid, crotonic acid,maleic acid, fumaric acid, and itaconic acid, with acrylic acid beingpreferred.

[0092] The softening comonomer that can be optionally included in theinner cover layer of the golf ball of the invention may be selected fromthe group consisting of vinyl esters of aliphatic carboxylic acidswherein the acids have 2 to 10 carbon atoms, vinyl ethers wherein thealkyl groups contain 1 to 10 carbon atoms, and alkyl acrylates ormethacrylates wherein the alkyl group contains 1 to 10 carbon atoms.Suitable softening comonomers include vinyl acetate, methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate,butyl methacrylate, or the like.

[0093] Consequently, examples of a number of copolymers suitable for useto produce the high acid ionomers included in the present inventioninclude, but are not limited to, high acid embodiments of anethylene/acrylic acid copolymer, an ethylene/methacrylic acid copolymer,an ethylene/itaconic acid copolymer, an ethylene/maleic acid copolymer,an ethylene/methacrylic acid/vinyl acetate copolymer, anethylene/acrylic acid/vinyl alcohol copolymer, etc. The base copolymerbroadly contains greater than 16% by weight unsaturated carboxylic acid,from about 39 to about 83% by weight ethylene and from 0 to about 40% byweight of a softening comonomer. Preferably, the copolymer containsabout 20% by weight unsaturated carboxylic acid and about 80% by weightethylene. Most preferably, the copolymer contains about 20% acrylic acidwith the remainder being ethylene.

[0094] Along these lines, examples of the preferred high acid basecopolymers which fulfill the criteria set forth above are a series ofethylene-acrylic copolymers which are commercially available from TheDow Chemical Company, Midland, Mich., under the Primacor® designation.

[0095] The metal cation salts utilized in the invention are those saltswhich provide the metal cations capable of neutralizing, to variousextents, the carboxylic acid groups of the high acid copolymer. Theseinclude acetate, oxide or hydroxide salts of lithium, calcium, zinc,sodium, potassium, nickel, magnesium, and manganese.

[0096] Examples of such lithium ion sources are lithium hydroxidemonohydrate, lithium hydroxide, lithium oxide and lithium acetate.Sources for the calcium ion include calcium hydroxide, calcium acetateand calcium oxide. Suitable zinc ion sources are zinc acetate dihydrateand zinc acetate, a blend of zinc oxide and acetic acid. Examples ofsodium ion sources are sodium hydroxide and sodium acetate. Sources forthe potassium ion include potassium hydroxide and potassium acetate.Suitable nickel ion sources are nickel acetate, nickel oxide and nickelhydroxide. Sources of magnesium include magnesium oxide, magnesiumhydroxide, and magnesium acetate. Sources of manganese include manganeseacetate and manganese oxide.

[0097] The metal cation neutralized high acid ionomer resins areproduced by reacting the high acid base copolymer with various amountsof the metal cation salts above the crystalline melting point of thecopolymer, such as at a temperature from about 200° F. to about 500° F.,preferably from about 250° F. to about 350° F. under high shearconditions at a pressure of from about 10 psi to 10,000 psi. Other wellknown blending techniques may also be used. The amount of metal cationsalt utilized to produce the new metal cation neutralized high acidbased ionomer resins is the quantity which provides a sufficient amountof the metal cations to neutralize the desired percentage of thecarboxylic acid groups in the high acid copolymer. The extent ofneutralization is generally from about 10% to about 90%.

[0098] A number of different types of metal cation neutralized high acidionomers can be obtained from the above indicated process. These includehigh acid ionomer resins neutralized to various extents with manganese,lithium, potassium, calcium and nickel cations. In addition, when a highacid ethylene/acrylic acid copolymer is utilized as the base copolymercomponent of the invention and this component is subsequentlyneutralized to various extents with the metal cation salts producingacrylic acid based high acid ionomer resins neutralized with cationssuch as sodium, potassium, lithium, zinc, magnesium, manganese, calciumand nickel, several cation neutralized acrylic acid based high acidionomer resins are produced.

[0099] When compared to low acid versions of similar cation neutralizedionomer resins, the metal cation neutralized high acid ionomer resinsexhibit enhanced hardness, modulus and resilience characteristics. Theseare properties that are particularly desirable in a number ofthermoplastic fields, including the field of golf ball manufacturing.

[0100] The low acid ionomers which may be suitable for use informulating the inner layer compositions of the subject invention areionic copolymers which are the metal (sodium, zinc, magnesium, etc.)salts of the reaction product of an olefin having from about 2 to 8carbon atoms and an unsaturated monocarboxylic acid having from about 3to 8 carbon atoms. Preferably, the ionomeric resins are copolymers ofethylene and either acrylic or methacrylic acid. In some circumstances,an additional comonomer such as an acrylate ester (for example, iso- orn-butylacrylate, etc.) can also be included to produce a softerterpolymer. The carboxylic acid groups of the copolymer are partiallyneutralized (for example, approximately 10 to 100%, preferably 30 to70%) by the metal ions. Each of the low acid ionomer resins which may beincluded in the inner layer cover compositions of the invention contains16% by weight or less of a carboxylic acid.

[0101] The inner layer compositions may include the low acid ionomerssuch as those developed and sold by E.I. DuPont de Nemours & Companyunder the trademark Surlyn® and by Exxon Corporation under thetrademarks Escor® or lotek®, ionomers made in-situ, or blends thereof.

[0102] In one embodiment of the inner cover layer, a blend of high andlow acid ionomer resins is used. These can be the ionomer resinsdescribed above, combined in a weight ratio which preferably is withinthe range of 10 to 90 to 90 to 10 percent high and low acid ionomerresins.

[0103] Another embodiment of the inner cover layer is a cover comprisinga non-ionomeric thermoplastic material or thermoset material. Suitablenon-ionomeric materials include, but are not limited to, metallocenecatalyzed polyolefins or polyamides, polyamide/ionomer blends,polyphenylene ether/ionomer blends, etc., which have a Shore D hardnessof at least 60 (or a Shore C hardness of at least about 90) and a flexmodulus of greater than about 30,000 psi, preferably greater than about50,000 psi, or other hardness and flex modulus values which arecomparable to the properties of the ionomers described above. Othersuitable materials include but are not limited to, thermoplastic orthermosetting polyurethanes, thermoplastic block polyesters, forexample, a polyester elastomer such as that marketed by DuPont under thetrademark Hytrel®, or thermoplastic block polyamides, for example, apolyether amide such as that marketed by Elf Atochem S.A. under thetrademark Pebax®, a blend of two or more non-ionomeric thermoplasticelastomers, or a blend of one or more ionomers and one or morenon-ionomeric thermoplastic elastomers. These materials can be blendedwith the ionomers described above in order to reduce cost relative tothe use of higher quantities of ionomer. Although Hytrel® and Pebax® aresometimes more expensive than certain ionomers, these materialstypically have higher densities than ionomers and have differentresiliency characteristics at low impacts, and so, may be desirable.

[0104] Additional materials suitable for use in the inner cover layer orsingle cover layer of the present invention include polyurethanes. Theseare described in more detail below.

[0105] Any number of inner layers may be used. Each layer may be thesame or different material as any other layer, and each may be of thesame or different thickness. One or more of the inner layers, ifapplicable, may also be the same as the outer cover layer.

[0106] A core with a hard inner cover layer formed thereon generallyprovides the multi-layer golf ball with resilience and distance. In onepreferred embodiment, the outer cover layer is comparatively softer thanthe inner cover layer. For a golf ball having a single cover layer and acore, the cover layer may be a soft cover layer, as described herein.The softness provides for the feel and playability characteristicstypically associated with balata or balata-blend balls.

[0107] The soft outer cover layer or ply is comprised of a relativelysoft, low flex modulus (about 500 psi to about 50,000 psi, preferablyabout 1,000 psi to about 25,000 psi, and more preferably about 5,000 psito about 20,000 psi) material or blend of materials. The outer coverlayer (or single cover layer, if applicable) comprises ionomers,non-ionomers, blends of ionomers, blends of non-ionomers and blends ofionomers and non-ionomers. Preferably, the outer cover layer comprises apolyurethane, a polyurea, a blend of two or morepolyurethanes/polyureas, or a blend of one or more ionomers or one ormore non-ionomeric thermoplastic materials with a polyurethane/polyurea,preferably a thermoplastic polyurethane or reaction injection moldedpolyurethane/polyurea (described in more detail below).

[0108] The outer layer is 0.0005 to about 0.15 inches in thickness,preferably about 0.001 to about 0.10 inches in thickness, and sometimesslightly thicker for a 1.72 inch (or more) ball, but thick enough toachieve desired playability characteristics while minimizing expense.Thickness is defined as the average thickness of the non-dimpled areasof the outer cover layer. The outer cover layer preferably has a Shore Dhardness of 60 or less (or less than 90 Shore C), and more preferably 55or less (or about 80 Shore C or less).

[0109] In another preferred embodiment, the outer cover layer iscomparatively harder than the inner cover layer. The outer layer iscomprised of a relatively hard, higher flex modulus (about 40,000 psi orgreater) material or blend of materials. The inner cover layer(s) may bea softer material such as a polyurethane or other non-ionomer, or ablend of materials, and the outer layer may be a harder material such asa harder ionomer, non-ionomer, or blend of materials.

[0110] Moreover, in alternative embodiments, either the inner and/or theouter cover layer (or single cover layer, if applicable) may alsoadditionally comprise up to 100 wt % of a soft, low modulus,non-ionomeric thermoplastic or thermoset material. Non-ionomericmaterials are suitable so long as they produce the playability anddurability characteristics desired without adversely affecting theproperties of the cover layer(s). These include, but are not limited to,styrene-butadiene-styrene block copolymers, including functionalizedstyrene-butadiene-styrene block copolymers,styrene-ethylene-butadiene-styrene (SEBS) block copolymers such asKraton® materials from Shell Chem. Co., and functionalized SEBS blockcopolymers; metallocene catalyzed polyolefins; ionomer/rubber blendssuch as those in Spalding U.S. Pat. Nos. 4,986,545; 5,098,105 and5,187,013; and, Hytrel® polyester elastomers from DuPont and Pebax®polyetheramides from Elf Atochem S.A.

[0111] The outer cover layer of the invention is formed over a core (andinner cover layer or layers if a multi-layer cover) to result in a golfball having a coefficient of restitution of at least 0.770, morepreferably at least 0.780, and most preferably at least 0.790. Thecoefficient of restitution of the ball will depend upon the propertiesof both the core and the cover. The PGA compression of the golf ball is100 or less, and preferably is 90 or less.

[0112] In one preferred embodiment, the outer cover layer comprises apolyurethane, a polyurea or a blend of polyurethanes/polyureas.Polyurethanes are polymers which are used to form a broad range ofproducts. They are generally formed by mixing two primary ingredientsduring processing. For the most commonly used polyurethanes, the twoprimary ingredients are a polyisocyanate (for example,4,4′-diphenylmethane diisocyanate monomer (“MDI”) and toluenediisocyanate (“TDI”) and their derivatives) and a polyol (for example, apolyester polyol or a polyether polyol).

[0113] A wide range of combinations of polyisocyanates and polyols, aswell as other ingredients, are available. Furthermore, the end-useproperties of polyurethanes can be controlled by the type ofpolyurethane utilized, such as whether the material is thermoset (crosslinked molecular structure not flowable with heat) or thermoplastic(linear molecular structure flowable with heat).

[0114] Cross linking occurs between the isocyanate groups (—NCO) and thepolyol's hydroxyl end-groups (—OH). Cross linking will also occurbetween the NH₂ group of the amines and the NCO groups of theisocyanates, forming a polyurea. Additionally, the end-usecharacteristics of polyurethanes can also be controlled by differenttypes of reactive chemicals and processing parameters. For example,catalysts are utilized to control polymerization rates. Depending uponthe processing method, reaction rates can be very quick (as in the casefor some reaction injection molding systems (“RIM”)) or may be on theorder of several hours or longer (as in several coating systems such asa cast system). Consequently, a great variety of polyurethanes aresuitable for different end-uses.

[0115] Polyurethanes are typically classified as thermosetting orthermoplastic. A polyurethane becomes irreversibly “set” when apolyurethane prepolymer is cross linked with a polyfunctional curingagent, such as a polyamine or a polyol. The prepolymer typically is madefrom polyether or polyester. A prepolymer is typically an isocyanateterminated polymer that is produced by reacting an isocyanate with amoiety that has active hydrogen groups, such as a polyester and/orpolyether polyol. The reactive moiety is a hydroxyl group. Diisocyanatepolyethers are preferred because of their water resistance.

[0116] The physical properties of thermoset polyurethanes are controlledsubstantially by the degree of cross linking and by the hard and softsegment content. Tightly cross linked polyurethanes are fairly rigid andstrong. A lower amount of cross linking results in materials that areflexible and resilient. Thermoplastic polyurethanes have some crosslinking, but primarily by physical means, such as hydrogen bonding. Thecrosslinking bonds can be reversibly broken by increasing temperature,such as during molding or extrusion. In this regard, thermoplasticpolyurethanes can be injection molded, and extruded as sheet and blowfilm. They can be used up to about 400° F. and are available in a widerange of hardnesses.

[0117] Polyurethane materials suitable for the present invention may beformed by the reaction of a polyisocyanate, a polyol, and optionally oneor more chain extenders. The polyol component includes any suitablepolyether- or polyester polyol. Additionally, in an alternativeembodiment, the polyol component is polybutadiene diol. The chainextenders include, but are not limited to, diols, triols and amineextenders. Any suitable polyisocyanate may be used to form apolyurethane according to the present invention. The polyisocyanate ispreferably selected from the group of diisocyanates including, but notlimited to, 4,4′-diphenylmethane diisocyanate (“MDI”); 2,4-toluenediisocyanate (“TDI”); m-xylylene diisocyanate (“XDI”); methylenebis-(4-cyclohexyl isocyanate) (“HMDI”); hexamethylene diisocyanate(“HDI”); naphthalene-1,5,-diisocyanate (“NDI”);3,3′-dimethyl-4,4′-biphenyl diisocyanate (“TODI”); 1,4-diisocyanatebenzene (“PPDI”); phenylene-1,4-diisocyanate; and 2,2,4- or2,4,4-trimethyl hexamethylene diisocyanate (“TMDI”).

[0118] Other less preferred diisocyanates include, but are not limitedto, isophorone diisocyanate (“IPDI”); 1,4-cyclohexyl diisocyanate(“CHDI”); diphenylether-4,4′-diisocyanate; p,p′-diphenyl diisocyanate;lysine diisocyanate (“LDI”); 1,3-bis (isocyanato methyl) cyclohexane;and polymethylene polyphenyl isocyanate (“PMDI”).

[0119] One additional polyurethane component which can be used in thepresent invention incorporates TMXDI (“META”) aliphatic isocyanate(Cytec Industries, West Paterson, N.J.). Polyurethanes based onmeta-tetramethylxylylene diisocyanate (TMXDI) can provide improved glossretention UV light stability, thermal stability, and hydrolyticstability. Additionally, TMXDI (“META”) aliphatic isocyanate hasdemonstrated favorable toxicological properties. Furthermore, because ithas a low viscosity, it is usable with a wider range of diols (topolyurethane) and diamines (to polyureas). If TMXDI is used, ittypically, but not necessarily, is added as a direct replacement forsome or all of the other aliphatic isocyanates in accordance with thesuggestions of the supplier. Because of slow reactivity of TMXDI, it maybe useful or necessary to use catalysts to have practical demoldingtimes. Hardness, tensile strength and elongation can be adjusted byadding further materials in accordance with the supplier's instructions.

[0120] The polyurethane which is selected for use as a golf ball coverpreferably has a Shore D hardness (plaque) of from about 10 to about 55(Shore C of about 15 to about 75), more preferably from about 25 toabout 55 (Shore C of about 40 to about 75), and most preferably fromabout 30 to about 55 (Shore C of about 45 to about 75) for a soft coverlayer and from about 20 to about 90, preferably about 30 to about 80,and more preferably about 40 to about 70 for a hard cover layer.

[0121] The polyurethane which is to be used for a cover layer preferablyhas a flex modulus from about 1 to about 310 Kpsi, more preferably fromabout 3 to about 100 Kpsi, and most preferably from about 3 to about 40Kpsi for a soft cover layer and 40 to 90 Kpsi for a hard cover layer.Accordingly, covers comprising these materials exhibit similarproperties. The polyurethane preferably has good light fastness.

[0122] Non-limiting examples of a polyurethane suitable for use in theouter cover layer (or inner cover layer) include a thermoplasticpolyester polyurethane such as Bayer Corporation's Texin® polyesterpolyurethane (such as Texin® DP7-1097 and Texin® 285 grades) and apolyester polyurethane such as B.F. Goodrich Company's Estane® polyesterpolyurethane (such as Estane® X-4517 grade). The thermoplasticpolyurethane material may be blended with a soft ionomer or othernon-ionomer. For example, polyamides blend well with soft ionomer.

[0123] Other soft, relatively low modulus non-ionomeric thermoplastic orthermoset polyurethanes may also be utilized to produce the outer coverlayers, or any of the inner cover layers, as long as the non-ionomericmaterials produce the playability and durability characteristics desiredwithout adversely affecting the enhanced travel distance characteristicproduced by the high acid ionomer resin composition. These include, butare not limited to thermoplastic polyurethanes such as the Pellethane®thermoplastic polyurethanes from Dow Chemical Co.; and non-ionomericthermoset polyurethanes including but not limited to those disclosed inU.S. Pat. No. 5,334,673 incorporated herein by reference.

[0124] Typically, there are two classes of thermoplastic polyurethanematerials: aliphatic polyurethanes and aromatic polyurethanes. Thealiphatic materials are produced from a polyol or polyols and aliphaticisocyanates, such as H₁₂MDI or HDI, and the aromatic materials areproduced from a polyol or polyols and aromatic isocyanates, such as MDIor TDI. The thermoplastic polyurethanes may also be produced from ablend of both aliphatic and aromatic materials, such as a blend of HDIand TDI with a polyol or polyols.

[0125] Generally, the aliphatic thermoplastic polyurethanes arelightfast, meaning that they do not yellow appreciably upon exposure toultraviolet light. Conversely, aromatic thermoplastic polyurethanes tendto yellow upon exposure to ultraviolet light. One method of stopping theyellowing of the aromatic materials is to paint the outer surface of thefinished ball with a coating containing a pigment, such as titaniumdioxide, so that the ultraviolet light is prevented from reaching thesurface of the ball. Another method is to add UV absorbers, opticalbrighteners and stabilizers to the clear coating(s) on the outer cover,as well as to the thermoplastic polyurethane material itself. By addingUV absorbers and stabilizers to the thermoplastic polyurethane and thecoating(s), aromatic polyurethanes can be effectively used in the outercover layer of golf balls. This is advantageous because aromaticpolyurethanes typically have better scuff resistance characteristicsthan aliphatic polyurethanes, and the aromatic polyurethanes typicallycost less than the aliphatic polyurethanes.

[0126] Other suitable polyurethane materials for use in the presentinvention golf balls include reaction injection molded (“RIM”)polyurethanes. RIM is a process by which highly reactive liquids areinjected into a mold, mixed usually by impingement and/or mechanicalmixing in an in-line device such as a “peanut mixer,” where theypolymerize primarily in the mold to form a coherent, one-piece moldedarticle. The RIM process usually involves a rapid reaction between oneor more reactive components such as a polyether polyol or polyesterpolyol, polyamine, or other material with an active hydrogen, and one ormore isocyanate-containing constituents, often in the presence of acatalyst. The constituents are stored in separate tanks prior to moldingand may be first mixed in a mix head upstream of a mold and theninjected into the mold. The liquid streams are metered in the desiredweight to weight ratio and fed into an impingement mix head, with mixingoccurring under high pressure, for example, 1,500 to 3,000 psi. Theliquid streams impinge upon each other in the mixing chamber of the mixhead and the mixture is injected into the mold. One of the liquidstreams typically contains a catalyst for the reaction. The constituentsreact rapidly after mixing to gel and form polyurethane polymers.Polyureas, epoxies, and various unsaturated polyesters also can bemolded by RIM.

[0127] Non-limiting examples of suitable RIM systems for use in thepresent invention are Bayflex® elastomeric polyurethane RIM systems,Baydur® GS solid polyurethane RIM systems, Prism® solid polyurethane RIMsystems, all from Bayer Corp. (Pittsburgh, Pa.), Spectrim® reactionmoldable polyurethane and polyurea systems from Dow Chemical USA(Midland, Mich.), including Spectrim® MM 373-A (isocyanate) and 373-B(polyol), and Elastolit® SR systems from BASF (Parsippany, N.J.).Preferred RIM systems include Bayflex® MP-10000, Bayflex® MP-7500 andBayflex® 110-50, filled and unfilled. Further preferred examples arepolyols, polyamines and isocyanates formed by processes for recyclingpolyurethanes and polyureas. Additionally, these various systems may bemodified by incorporating a butadiene component in the diol agent.

[0128] Another preferred embodiment is a golf ball in which at least oneof the inner cover layer and/or the outer cover layer comprises afast-chemical-reaction-produced component. This component comprises atleast one material selected from the group consisting of polyurethane,polyurea, polyurethane ionomer, epoxy, and unsaturated polyesters, andpreferably comprises polyurethane, polyurea or a blend comprisingpolyurethanes and/or polymers. A particularly preferred form of theinvention is a golf ball with a cover comprising polyurethane or apolyurethane blend.

[0129] The polyol component typically contains additives, such asstabilizers, flow modifiers, catalysts, combustion modifiers, blowingagents, fillers, pigments, optical brighteners, and release agents tomodify physical characteristics of the cover. Polyurethane/polyureaconstituent molecules that were derived from recycled polyurethane canbe added in the polyol component.

[0130] A golf ball inner cover layer or single cover layer according tothe present invention formed from a polyurethane material typicallycontains from about 0 to about 60 weight percent of filler material,more preferably from about 1 to about 30 weight percent, and mostpreferably from about 1 to about 20 weight percent.

[0131] A golf ball outer cover layer according to the present inventionformed from a polyurethane material typically contains from about 0 toabout 20 weight percent of filler material, more preferably from about 1to about 10 weight percent, and most preferably from about 1 to about 5weight percent.

[0132] Additional materials may also be added to the inner and outercover layer of the present invention as long as they do notsubstantially reduce the playability properties of the ball. Suchmaterials include dyes and/or optical brighteners (for example,Ultramarine Blue™ sold by Whittaker, Clark, and Daniels of SouthPlainsfield, N.J.) (see U.S. Pat. No. 4,679,795); pigments such astitanium dioxide, zinc oxide, barium sulfate and zinc sulfate; UVabsorbers; antioxidants; antistatic agents; and stabilizers. Moreover,the cover compositions of the present invention may also containsoftening agents such as those disclosed in U.S. Pat. Nos. 5,312,857 and5,306,760, including plasticizers, metal stearates, processing acids,and the like, and reinforcing materials such as glass fibers andinorganic fillers, as long as the desired properties produced by thegolf ball covers of the invention are not impaired.

[0133] Core Layer(s)

[0134] The core of the golf ball can be formed of a solid, a liquid, orany other substance that will result in a core or an inner ball (coreand at least one inner cover layer, if the ball is a multi-layer ball),having the desired COR, compression and hardness and other physicalproperties.

[0135] The cores of the inventive golf balls typically have acoefficient of restitution of about 0.750 or more, more preferably 0.770or more and a PGA compression of about 90 or less, and more preferably70 or less. Furthermore, in some applications it may be desirable toprovide a core with a coefficient of restitution of about 0.780 to 0.790or more.

[0136] The core used in the golf ball of the invention preferably is asolid, but any core type known in the art may be used, such as wound,liquid, hollow, metal, and the like. The term “solid cores” as usedherein refers not only to one piece cores but also to those cores havinga separate solid layer beneath the covers and over the central core. Thecores generally have a weight of about 25 to about 40 grams andpreferably about 30 to about 40 grams. Larger and heavier cores, orlighter and smaller cores, may also be used when there is no desire tomeet U.S.G.A. or R. & A. standards.

[0137] When the golf ball of the invention has a solid core, this corecan be compression molded from a slug of uncured or lightly curedelastomer composition comprising a high cis content polybutadiene and ametal salt of an α, β, ethylenically unsaturated carboxylic acid such aszinc mono- or diacrylate or methacrylate. To achieve higher coefficientsof restitution and/or to increase hardness in the core, the manufacturermay include a small amount of a metal oxide such as zinc oxide. Inaddition, larger amounts of metal oxide than are needed to achieve thedesired coefficient may be included in order to increase the core weightso that the finished ball more closely approaches the U.S.G.A. upperweight limit of 1.620 ounces.

[0138] Non-limiting examples of other materials which may be used in thecore composition include, but are not limited to, compatible rubbers orionomers, and low molecular weight fatty acids such as stearic acid.Free radical initiator catalysts such as peroxides may be admixed withthe core composition so that on the application of heat and pressure, acuring or cross-linking reaction takes place. The core may also beformed from any other process for molding golf ball cores known in theart.

[0139] A thread wound core may comprise a liquid, solid, gel ormulti-piece center. The thread wound core is typically obtained bywinding a thread of natural or synthetic rubber, or thermoplastic orthermosetting elastomer such as polyurethane, polyester, polyamide, etc.on a solid, liquid, gel or gas filled center to form a thread rubberlayer that is then covered with one or more mantle or cover layers.Additionally, prior to applying the cover layer(s), the thread woundcore may be further treated or coated with an adhesive layer, protectivelayer, or any substance that may improve the integrity of the wound coreduring application of the cover layers and ultimately in usage as a golfball.

[0140] Since the core material is not an integral part of the presentinvention, a detailed discussion concerning the specific types of corematerials which may be utilized with the cover compositions of theinvention are not specifically set forth herein.

[0141] Manufacturing Golf Balls

[0142] The golf balls of the present invention eliminate or reduce theneed for retractable pins to support the core (or core and inner coverlayer(s)) in the mold. There may be, however, “knock out” pins in themold that are useful in extracting the part from the mold. In the priorart, retractable pins have been used to support the core or core andadditional layers. The pins hold the core in place until enough covermaterial fills the mold to support the core without assistance, at whichtime the pins are retracted. Molding golf balls without the use ofretractable pins reduces the amount of additional processing necessaryon a finished ball. Additionally, there is no need to clean the moldfrequently because of build up of cover material on the retractable moldpins.

[0143] In accordance with a preferred technique of the invention, one ormore deep dimples are formed that extend to or into various internallayers or components of a golf ball. Specifically, each layer hasdimples formed therein by a dimpled cavity having a pattern having thesame geometric coordinates as other corresponding dimpled cavities. Thecore or core and inner layer(s) need to be aligned such that the dimplesare formed over one another in the subsequent layers.

[0144] For example, for a dimple in a preferred embodiment ball of thepresent invention, the outer layer may account for a portion of thetotal depth, and the inner layer(s) will account for the remainder. In atraditional prior art ball, the dimple depth, which is generally about0.010 inches, is generally less than the thickness of the cover so thatthe dimple does not touch or extend to the next layer or even come closeto the next layer. Therefore, there is a minimum cover thickness thatcan be used in order to have dimples of the desired depth. The golf ballof the present invention eliminates the need to have a cover thicknessgreater than the desired dimple depth because two or more layers canmake up the dimple, and thus, each layer may be very thin (less than0.010 inches).

[0145] Furthermore, the golf balls of the present invention mayincorporate both deep dimples and dual dimples (dimple within a dimple)or dimples formed in multiple layers, as previously described.

[0146] In preparing golf balls in accordance with a preferred embodimentof the present invention, a single cover layer or an inner cover layer(or mantle layer) is molded about a core (preferably a solid core). Thecover layer(s) may be molded using any molding processing known in theart. Examples of molding processes include, but are not limited to,injection molding, transfer molding, reaction injection molding, liquidinjection molding, casting, compression molding, and the like.

[0147] For a multi-layer ball, as shown in FIGS. 3 and 4, an outer layer160 is molded over the inner layer 150. The core (or core and innerlayer(s)) is supported by one or more, preferably two or more, supportpins or protrusions which form the deep dimples that contact the core orintermediate ball assembly. That is, the exterior surface of the supportpins or protrusions form the inner surface of the deep dimples.

[0148] The core (or core and inner layer(s)) is held in place by aholding force created by designing the dimples, or rather the raisedprojections on a molding surface that form such dimples, deep enough togrip the ball by slightly pre-loading the core or intermediate ballassembly. Ignoring friction, the only force generated is in the radialdirection, and radial pre-load force is proportional to radialinterference between the deep dimples and the core or core and innerlayer(s).

[0149] The number of deep dimples on a golf ball of the presentinvention may vary as desired. Any number and pattern of deep dimplesmay be used, although a limited number of deep dimples in a specificgeometric pattern is preferred. The geometric pattern is preferablyapproximately centered about the pole of the ball. Given the limitednumber of coordinates or points, it is generally not possible to exactlycenter certain geometric patterns with some shapes, such as a triangle.Additionally, it may be desirable to shift the pattern slightly toaccommodate different forces (due to the molding of the layer(s)) ondifferent sides of the ball.

[0150]FIGS. 9 and 10 are top views (one hemisphere of the ball) of agolf ball having certain preferred arrangements of deep dimples. FIG. 9illustrates a golf ball 610 having a triangular arrangement of threedeep dimples 42 located approximately symmetrically around a pole 44.FIG. 10 illustrates a golf ball 710 having a diamond shaped arrangementof four deep dimples 42 located approximately symmetrically around apole 44. The figures are for illustrative purposes since any desirednumber of deep dimples may be used, such as one, two, three, four, five,six and the like. The deep dimples do not have to be symmetricallylocated, although symmetry enhances their aerodynamic effect. Thisresults in a finished ball where the deep dimples extend from the outerlayer into the next inner layer(s) and/or the core. Multiple coverlayers, of the same or different materials and thicknesses, may be addedto the ball using this procedure. The deep dimples may extend intomultiple layers if there are multiple layers on the ball, if desired.

[0151] The deep dimple locations may be anywhere on the ball, such as atabout 30 degrees latitude on each hemisphere, about 40 to 45 degreeslatitude, about 50 to 60 degrees latitude, and the like. That is, thedeep dimples may be within a region along the outer surface of a ballfrom about 30 degrees latitude to about 60 degrees latitude in either orboth hemispheres. Preferably, the deep dimples are located at about 40to 45 degrees latitude or more on each hemisphere. As used herein,latitude refers to the location of the dimple on the ball, with theequator defined as 0 degrees latitude, and each pole of the ball definedas 90 degrees latitude.

[0152]FIG. 13 is a graph illustrating the relationship between thelocation of these deep dimples on a ball and the resulting force appliedto the core. Table 1, set forth below lists the data that is illustratedgraphically in FIG. 13. TABLE 1 Angle Lateral Vertical deg % Radial %Radial 0 100% 0% 5 100% 9% 10 98% 17% 15 97% 26% 20 94% 34% 25 91% 42%30 87% 50% 35 82% 57% 40 77% 64% 45 71% 71% 50 64% 77% 55 57% 82% 60 50%87% 65 42% 91% 70 34% 94% 75 26% 97% 80 17% 98% 85 9% 100% 90 0% 100%

[0153] In another preferred embodiment, the core or intermediate ball(core plus one or more mantle or inner cover layer(s)) is supported byone or more deep dimples that nearly contact or extend to the core. Thedeep dimple locations may be anywhere on the ball, such as at about 30degrees latitude on each hemisphere, about 40 to 45 degrees latitude,about 50 to 60 degrees latitude, and the like. Preferably, the deepdimples are located at about 40 to 45 degrees latitude or more on eachhemisphere. The number of deep dimples may vary as desired. Any numberand pattern may be used, although a limited number in a specificgeometric pattern is preferred. The geometric pattern should preferablybe approximately centered about the pole of the ball. It is not possibleto exactly center the geometric pattern with some shapes, such as atriangle. Additionally, it may be desirable to shift the patternslightly to accommodate different forces (due to the molding of thelayer(s)) on different sides of the ball. This results in a finishedball where the deep dimples extend from the outer layer to the nextinner layer or the core. As described above, multiple cover layers, ofthe same or different materials and thicknesses, may be added to theball using this procedure.

[0154]FIG. 14 is a perspective view of a preferred embodiment golf ballaccording to the present invention. This illustration reveals acircumferential region defined along the outer surface of the ball. Thisregion corresponds to the preferred location within which are definedone or more deep dimples as described herein. Specifically, thepreferred location for the deep dimples is the region along the outersurface of the ball extending between about 30° latitude and about 60°latitude. The pole of the ball is an axis extending through the ballshown in FIG. 14 as line P-P. The equator is illustrated in FIG. 14 as acircumferential line E extending about the ball at a latitude of 0°.

[0155] Any number of cover and/or mantle layers may be used, and thedeep dimples may extend into as many layers as desired. For example, agolf ball having a core and three cover layers (a first inner coverlayer, a second inner cover layer, and an outer cover layer) may beproduced according to the present invention. The deep dimples may extendto or through the first inner cover layer, through both the first innerlayer and the second inner cover layer, or, the deep dimple may extendthrough all the cover layers to or into the core.

[0156] Additionally, if desired, the mantle layer could be colored orcontain other visible or cosmetic features that could be seen throughthe cover layer. The cover layer may also be transparent, translucent oropaque if desired to enhance or highlight the mantle layer.

[0157] Other methods of molding golf balls without the use of core pinsinclude the use of tabs on the equator of the core such that the dimpledcavity can receive the tabs to hold the core in place. Alternatively,the golf ball may be molded with a mantle having one or more keyways oropenings. The cover mold would then be equipped with side pulls thatengage the keys and hold the core in place.

[0158] The core, preferably a solid core, for the ball is preferablyabout 1.2 to about 1.6 inches in diameter, although it may be possibleto use cores in the range of about 1.0 to 2.0 inches. If the ball has asingle cover layer, the core size may be up to about 1.660 inches.

[0159] The present invention includes one or more auxiliary layersdisposed on the core, and preferably immediately adjacent to the outercore surface. For example, for some applications, it may be preferred todeposit a barrier coating that limits transmission of moisture to thecore. As previously noted, such barrier coatings or layers arerelatively thin. Generally, such coatings are at least 0.0001 inches,and preferably, at least 0.003 inches in thickness. Furthermore, anadhesion promoting layer may be used between the cover layers and/or thecore, or the cover and core having a barrier coating disposed thereon.Such adhesion promoting layers are known in the art and may be used incombination with the inventive features described herein. See forexample U.S. Pat. No. 5,820,488 herein incorporated by reference.

[0160] The inner cover layer that is molded over the core is preferablyabout 0.0005 inches to about 0.15 inches. The inner ball that includesthe core and inner cover layer(s), or core for a two piece ball,preferably has a diameter in the range of 1.25 to 1.60 inches. The outercover layer is about 0.0005 inches to about 0.15 inches thick. Together,the core, the inner cover layer(s) and the outer cover layer (or coreand single cover layer) combine to form a ball having a diameter of1.680 inches or more, the minimum diameter permitted by the rules of theU.S.G.A and weighing no more than 1.62 ounces. If desired, golf balls ofdifferent weights and diameters may also be formed if the rules of theU.S.G.A. are not an issue.

[0161] In a particularly preferred embodiment of the invention, the golfball has a dimple pattern that provides dimple coverage of 65% or more,preferably 75% or more, and more preferably about 80 to 85% or more. Ina preferred embodiment of the invention, there are from 300 to less than500 dimples, preferably from about 340 to about 440 dimples.

[0162] Specifically, the arrangement and total number of dimples are notcritical and may be properly selected within ranges that are well known.For example, the dimple arrangement may be an octahedral, dodecahedralor icosahedral arrangement. The total number of dimples is generallyfrom about 250 to about 600, and especially from about 300 to about 500.

[0163] In a preferred embodiment, the golf ball typically is coated witha durable, abrasion-resistant, relatively non-yellowing finish coat orcoats if necessary. The finish coat or coats may have some opticalbrightener and/or pigment added to improve the brightness of thefinished golf ball. In a preferred embodiment, from 0.001 to about 10%optical brightener may be added to one or more of the finish coatings.If desired, optical brightener may also be added to the cover materials.One type of preferred finish coatings are solvent based urethanecoatings known in the art. It is also contemplated to provide atransparent outer coating or layer on the final finished golf ball.

[0164] Golf balls also typically include logos and other markingsprinted onto the dimpled spherical surface of the ball. Paint, typicallyclear paint, is applied for the purposes of protecting the cover andimproving the outer appearance before the ball is completed as acommercial product. FIG. 11 is a fragmental enlarged view showing theradial cross-sectional shape of a dimple formed in the surface of a golfball prior to paint coating. Most often, the dimple is circular in planeshape. In general, dimples such as the deep dimples shown in FIG. 11,are formed in a golf ball surface as a recess or indentation. Thecross-sectional shape of a dimple is defined by a portion of a curvedsurface such as a circle, ellipse, or hyper ellipse. For example, thecross-sectional shape of the dimple in FIG. 11 is a portion of a circle.The dimple is circumscribed by an upper edge which is continuouslyconnected to a land area of the outer surface of the golf ball where nodimples are formed. The edge is generally beveled from the land area asa steep slope to form the dimple. The edge is generally initiallyangular prior to paint coating and somewhat rounded after paint coating.

[0165] The various cover composition layers of the present invention maybe produced according to conventional melt blending procedures or anyother method known in the art. For example, the cover materials may beblended in a Banbury® type mixer, two-roll mill, or extruder prior toneutralization. After blending, neutralization then occurs in the meltor molten state in the Banbury® mixer. The blended composition is thenformed into slabs, pellets, etc., and maintained in such a state untilmolding is desired. Alternatively, a simple dry blend of the pelletizedor granulated materials (which have previously been neutralized to adesired extent, if applicable) and colored master batch may be preparedand fed directly into the injection molding machine where homogenizationoccurs in the mixing section of the barrel prior to injection into themold. If necessary, further additives such as an inorganic filler, etc.,may be added and uniformly mixed before initiation of the moldingprocess.

[0166] The golf balls of the present invention can be produced bymolding processes which include, but are not limited to, those which arecurrently well known in the golf ball art. As mentioned above, the golfballs can be produced, for example, by injection molding, reactioninjection molding (RIM), liquid injection molding, compression molding,and the like, the novel cover compositions around a wound, solid orother type of core to produce an inner ball which typically has adiameter of about 1.50 to 1.67 inches.

[0167] Alternatively, the cover layer(s) may be cast around the core orcore and inner layer(s), such as in a cast polyurethane system. Theouter layer is subsequently molded over the inner layer to produce agolf ball having a diameter of 1.620 inches or more, preferably about1.680 inches or more. This is currently a less preferred process sinceit is more difficult to cast mold around the deep dimple protrusions.Although any type of core, such as either solid cores or wound cores canbe used in the present invention, as a result of their lower cost andsuperior performance, solid molded cores are preferred over wound cores.The standards for both the minimum diameter and maximum weight of theballs are established by the United States Golf Association (U.S.G.A.),but not all golf balls are designed to meet these standards.

[0168] In compression molding, smooth surfaced hemispherical shells(previously molded) are positioned around the core in a mold having thedesired inner cover thickness. The core and shells are then subjected tocompression molding at about 200° F. to 300° F. for about 2 to 10minutes, followed by cooling at 50° F. to 70° F. for about 2 to 7minutes to fuse the shells together to form a unitary intermediate ball.In addition, the intermediate balls may be produced by injection moldingwherein the inner cover layer is injected directly around the coreplaced at the center of an intermediate ball mold for a period of timein a mold temperature of from 50° F. to about 100° F. Subsequently, theouter cover layer is molded about the core and the inner layer bysimilar molding techniques to form a dimpled golf ball of a diameter of1.680 inches or more. To improve the adhesion between the inner coverlayer and the outer cover layer, or any of the cover layers and/or thecore, an adhesion promoter may be used. Some adhesion promoters, such asabrasion of the surface, corona treatment, and the like, are known inthe art. A preferred adhesion promoter is a chemical adhesion promoter,such as a silane or other silicon compound, preferablyN-(2-aminoethyl-3)-aminopropyltrimethoxysilane. The intermediate golfball (core and inner cover layer) may be dipped or sprayed with thechemical, and then the outer cover layer is formed over the treatedinner cover layer. For multiple cover layers, the ball may be treatedmore than once if necessary or desired.

[0169] A typical process for casting covers around a core or core andinner layer(s) comprises two part (for example, bookcase type) moldsthat are heated to approximately 80 to 180° F. The cover material, suchas a polyurethane, is heated to approximately 80 to 180° F. The materialgel time is approximately 20 to 90 seconds, and mold closure time (heatstep) is approximately 2 to 8 minutes, and the cooling step isapproximately 2 to 8 minutes. After the material forms a cover, themolds are opened, and the balls are removed from the molds. The cavitiesmay optionally be cleaned and/or coated with a mold release before theprocess is repeated.

[0170] After molding, the golf balls produced may undergo variousfurther processing steps such as buffing, trimming, milling, tumbling,painting and marking as disclosed in U.S. Pat. No. 4,911,451, hereinincorporated by reference.

[0171] The resulting golf ball is produced more efficiently and lessexpensively than balls of the prior art. Additionally, the golf balls ofthe present invention may have multiple cover layers, some of them verythin (less than 0.03 inches, more preferably less than 0.02 inches, evenmore preferably less than 0.01 inches) if desired, to produce golf ballshaving specific performance characteristics. For example, golf ballshaving softer outer cover layer(s) and harder inner cover layer(s) maybe produced. Alternatively, golf balls having harder outer coverlayer(s) and softer inner cover layer(s) may be produced. Moreover, golfballs having inner and outer cover layers with similar hardnesses arealso anticipated by the present invention.

[0172] For golf balls have three or more layers, the hardness of thelayers may be varied alternately, such as hard-soft-hard, orsoft-hard-soft, and the like, or golf balls with a cover having ahardness gradient may be produced. The hardness gradient may start withhard inner layers closest to the core and get softer at the outer layer,or vice versa. This allows a lot of flexibility and control of finishedgolf ball properties. As previously described, the layers may be of thesame or different materials, and of the same or different thicknesses.

[0173] Additionally, golf balls of the present invention that comprisepolyurethane/polyurea (or other suitable materials) in any of the innerand outer cover layer may be produced by a reaction injection moldingprocess (RIM), as previously described.

[0174] Golf balls and, more specifically, cover layers formed by RIM arepreferably formed by the process described in application Ser. No.09/040,798, filed Mar. 18, 1998, incorporated herein by reference, or bya similar RIM process.

[0175] RIM differs from non-reaction injection molding in a number ofways. The main distinction is that in RIM a chemical reaction takesplace in the mold to transform a monomer or adducts to polymers and thecomponents are in liquid form. Thus, a RIM mold need not be made towithstand the pressures that occur in conventional injection molding.

[0176] In contrast, injection molding is conducted at high moldingpressures in the mold cavity by melting a solid resin and conveying itinto a mold, with the molten resin often being at about 150 to about350° C. At this elevated temperature, the viscosity of the molten resinusually is in the range of about 50,000 to about 1,000,000 centipoise,and is typically around 200,000 centipoise. In an injection moldingprocess, the solidification of the resins occurs after about 10 to about90 seconds, depending upon the size of the molded product, thetemperature and heat transfer conditions, and the hardness of theinjection molded material. Subsequently, the molded product is removedfrom the mold. There is no significant chemical reaction taking place inan injection molding process when the thermoplastic resin is introducedinto the mold.

[0177] In contrast, in a RIM process, the chemical reaction causes thematerial to set in less than about 5 minutes, often in less than 2minutes, preferably in less than one minute, more preferably in lessthan 30 seconds, and in many cases in about 10 seconds or less.

[0178] Catalysts can be added to the RIM polyurethane system startingmaterials as long as the catalysts generally do not react with theconstituent with which they are combined. Suitable catalysts includethose which are known to be useful with polyurethanes and polyureas.

[0179] The polyol component typically contains additives, such asstabilizers, flow modifiers, catalysts, combustion modifiers, blowingagents, fillers, pigments, optical brighteners, and release agents tomodify physical characteristics of the cover. Recycledpolyurethane/polyurea also can be added to the core.Polyurethane/polyurea constituent molecules that were derived fromrecycled polyurethane can be added in the polyol component.

[0180] The mold cavity contains support pins and is generallyconstructed in the same manner as a mold cavity used to injection mold athermoplastic, for example, ionomeric golf ball cover. However, twodifferences when RIM is used are that tighter pin tolerances generallyare required, and a lower injection pressure is used. Also, the moldscan be produced from lower strength material such as aluminum.

[0181] The RIM process may provide for improved cover layers. If plasticproducts are produced by combining components that are preformed to someextent, subsequent failure can occur at a location on the cover which isalong the seam or parting line of the mold, as well as at core pinlocations, because these regions are intrinsically different from theremainder of the cover layer and can be weaker or more stressed. Coverlayers produced via RIM are believed to provide for improved durabilityof a golf ball cover layer by providing a uniform or “seamless” cover inwhich the properties of the cover material in the region along theparting line are generally the same as the properties of the covermaterial at other locations on the cover, including at the poles. Theimprovement in durability is believed to be a result of the fact thatthe reaction mixture is distributed uniformly into a closed mold. Thisuniform distribution of the injected materials reduces or eliminatesknit-lines and other molding deficiencies which can be caused bytemperature differences and/or reaction differences in the injectedmaterials. RIM typically results in generally uniform molecularstructure, density and stress distribution as compared to conventionalinjection-molding processes.

[0182] The golf balls, and particularly the cover layer(s), of thepresent invention may also be formed by liquid injection molding (LIM)techniques, or any other method known in the art.

[0183] The golf balls formed according to the present invention can becoated using a conventional two-component spray coating or can be coatedduring the RIM process, for example, using an in-mold coating process.

[0184]FIG. 15 illustrates a preferred embodiment molding apparatus 1000in accordance with the present invention. Molding apparatus 1000comprises two mold halves 1020 and 1040 that each define a hemisphericalportion of a molding chamber 1024 and 1044. Defined along the outersurface of the hemispherical portion of the molding chamber 1024, are aplurality of raised protrusions or support pins 1032. These raisedregions or support pins form dimples in a cover layer in a golf ballformed using molding apparatus 1000. Also provided along the outersurface of the hemispherical molding chamber 1024 are a plurality ofraised regions or support pins 1026, 1028, and 1030. These raisedregions are of a height greater than the height of the raised regions1032. Specifically, the raised regions 1026, 1028, and 1030 form deepdimples as described herein. These raised regions are used to retain andsupport a golf ball core (or intermediate ball assembly) placed in themold. A passage 1022 is provided in the mold half 1020 as will beappreciated. The passage 1022 provides communication and a path for aflowable moldable material to be introduced into the molding chamber.The molding apparatus 1000 also includes a second molding portion orplate 1040. The plate 1040 defines a hemispherical molding chamber 1044also having a plurality of raised regions or support pins along itsouter surface. Specifically, raised regions 1046 and 1048 are providedsimilar to the previously described raised regions 1026, 1028, and 1030.The molding plate 1040 also defines a channel 1042 extending from themolding chamber 1044 to the exterior of the plate. Most preferably, themolding channel 1042 is aligned with channel 1022 in the other plate1020 when the mold is closed to provide a unitary passage providingcommunication between the molding chamber and the exterior of the mold.A golf ball core placed in the molding chamber 1020,1040 is supported bythe various raised regions 1026, 1028, 1030, 1046, and 1048 aspreviously described. A golf ball 1010 or ball component is produced.

[0185] In regards to forming a variety of golf balls, the presentinvention also provides a process for forming a golf ball having atleast one deep dimple. Preferably, this process is as follows. Anintermediate golf ball assembly such as including a core or a coreand/or one or more intermediate layers disposed thereon, is provided. Amolding apparatus is also provided for molding an outer or cover layerabout the intermediate golf ball assembly. The molding apparatusincludes a generally spherical molding chamber having a first populationor collection of raised regions defined along a molding surface forforming a plurality of dimples on the outer layer of the golf ball. Themolding chamber also includes at least one other raised region orcollection of raised regions all of which have a height that is equal toor greater than the thickness of the outer layer to be formed on thegolf ball. The process also includes a step of positioning theintermediate golf ball assembly in the molding chamber and administeringa flowable material such as a flowable cover layer material to themolding apparatus. The material is introduced such that it flows aroundthe intermediate golf ball assembly disposed in the molding chamber.Preferably, the process also includes a step of hardening or curing theflowable material to thereby form the outer layer. A key feature of thistechnique is that upon positioning the intermediate golf ball assemblyin the molding chamber, the other raised region(s) of the moldingchamber contacts and preferably supports the intermediate golf ballassembly while positioned within the molding chamber.

[0186] Specifically, the golf ball of the present invention is notparticularly limited with respect to its structure and construction. Byusing well known ball materials and conventional manufacturingprocesses, the balls may be manufactured as solid golf balls includingone-piece golf balls, two-piece golf balls, and multi-piece golf ballswith three or more layers and wound golf balls.

[0187] The present invention is further illustrated by the followingexamples in which the parts of the specific ingredients are by weight.It is to be understood that the present invention is not limited to theexamples, and various changes and modifications may be made in theinvention without departing from the spirit and scope thereof.

EXAMPLES

[0188] Golf balls according to the present invention were produced. Thegolf balls had a core, a mantle or inner cover layer, and an outer coverlayer. The mantle was an ionomer, and the outer cover was a polyurethanecover formed by a RIM process (Ball Type A). The mold used had 6 supportpins (3 in each hemisphere), which formed deep dimples in eachhemisphere, located in a triangular arrangement similar to that shown inFIG. 9. The balls were tested against other balls, as described below.The results are shown in Tables 3 to 5 below.

[0189] Ball Type B was a ball having a dual core, an ionomer mantle andan injection molded polyurethane cover. Ball Type C was a ball having asingle core, an ionomer mantle and an ionomer cover. Ball Type D was acommercial grade Strata® Tour Professional™ ball, Ball Type E was acommercial grade Top-Flite® Z-Balata™ 90 golf ball, Ball Type F was acommercial grade Nike® Tour Accuracy TW™ ball, and Ball Type G was acommercial grade Titleist® Pro VI™ ball.

[0190] Coefficient of restitution (C.O.R.) was measured by firing theresulting golf ball in an air cannon at a velocity of 125 feet persecond against a steel plate positioned 12 feet from the muzzle of thecannon. The rebound velocity was then measured. The rebound velocity wasdivided by the forward velocity to give the coefficient of restitution.

[0191] The scuff resistance test was conducted in the manner describedbelow. The balls that were tested were primed and top coated. A sharpgrooved sand wedge (56 degrees loft) was mounted in a mechanical swingmachine. The club swing speed used was 60 mph. After each hit, the clubface was brushed clean using a nylon bristled brush. A minimum of threesamples of each ball was tested. Each ball was hit three times at threedifferent locations so as not to overlap with other strikes. The detailsof the club face are critical, and are as follows:

[0192] Groove width—0.025 inches (cut with a mill cutter, leaving asharp edge to the groove; no sandblasting or post finishing should bedone after milling);

[0193] Groove depth—0.016 inches;

[0194] Groove spacing (one groove edge to the nearest adjacentedge)—0.105 inches.

[0195] For each strike, a point value should be assigned for the worsttwo defects according to the following Table 2: TABLE 2 Point ValueShear Defect 0 No visible defects 0.5 Lines 1 Lifts 2 Bad Lifts 2 Tiny(or Paint) Hairs 3 Bad Hairs 3 Shears (if land area is removed on “hard”covers (65 Shore D+), rank as the only defect 6 (max value) Bad Shears(dimples are completely removed, rank as the only defect) Example - astrike having a shear, tiny hairs, bad lifts and a line would be rankedas a 5 (3 points for a shear and 2 points for tiny hairs)

[0196] After completing all strikes, the average point value wasdetermined. This average point value, or rank, can be correlated to thechart below. Rank Average Point Value Excellent 0.0-1.0 Very Good1.1-2.0 Good 2.1-3.0 Fair 3.1-4.0 Borderline 4.1-5.0 Poor (unacceptable)5.1-6.0

[0197] Cut resistance was measured in accordance with the followingprocedure: A golf ball was fired at 135 feet per second against theleading edge of a pitching wedge wherein the leading edge radius was{fraction (1/32)} inch, the loft angle was 51 degrees, the sole radiuswas 2.5 inches and the bounce angle was 7 degrees.

[0198] The cut resistance of the balls tested herein was evaluated on ascale of 1 to 5. The number 1 represents a cut that extends completelythrough the cover to the core. A 2 represents a cut that does not extendcompletely through the cover but that does break the surface. A 3 doesnot break the surface of the cover but does leave a permanent dent. A 4leaves only a slight crease which is permanent but not as severe as 3. A5 represents virtually no visible indentation or damage of any sort.

[0199] Cut and scuff testing was conducted on the golf balls of theinvention (Ball Type A), two experimental golf balls (Ball Types B andC), and two commercial grade golf balls (Ball Types F and G).

[0200] Initial velocity is the velocity of a ball when struck at ahammer speed of 143.8 feet per second in accordance with a test asprescribed by the U.S.G.A.

[0201] As used herein, “Shore D hardness” or “Shore C hardness” of acore or cover component is measured generally in accordance with ASTMD-2240, except the measurements are made on the curved surface of themolded component, rather than on a plaque. Furthermore, the Shore C andD hardness of the cover is measured while the cover remains over thecore. When a hardness measurement is made on a dimpled cover, Shore C orShore D hardness is measured at a land area of the dimpled cover.

[0202] Spin rate testing was conducted with the finished multi-layergolf balls (Ball Type A) of the invention, as well as two otherexperimental multi-layer cover golf balls (Ball Types B and C) using adriver, a 5 iron, a 9 iron, and a pitching wedge.

[0203] For comparative purposes, two commercial grade golf balls (BallTypes D and E) were also tested. The golf ball testing machine was setup to emulate the launch conditions of an average touring professionalgolfer for each particular club. TABLE 3 Ball Constructions and TestResults Nez Ball Size Weight Riehle Comp Fac- Cut Type (inches) (grams)Comp (PGA) COR tor Rank Scuff A 1.683 45.5 80 80 0.801 881 3   4* B1.684 45.5 81 79 0.808 889 3  6 C 1.685 45.4 79 81 0.808 887 3 5.8  D1.684 45.4 80 80 0.800 880 — — E — — — — — — 5  6 F — — — — — — 2 2.7*

[0204] Note that Ball Type A had cut and scuff results as good as, ifnot better than, most of the other ball types.

[0205] Below are the results of the spin rate and distance testing:TABLE 4 Spin Rate Data (average for 12 hits per ball type) Launch TotalSpin Rate Ball Velocity Club Ball Type Angle (rpm) (ft./sec.) Hogan A10.3 2442 235.0 Prototype B 10.1 2776 236.0 Driver C 10.1 2776 236.5 D(Strata ® Tour 10.0 2660 235.4 Professional) E (Z-Balata 90) 10.0 2928230.8

[0206] TABLE 5 Distance Data (average for 12 hits per ball type) PeakFlight Total Ball Trajec- Time Time Carry Roll Distance Club Type tory(sec) (sec) (yards) (yards) (yards) Hogan A 29.9 1.91 6.61 254.1 6.4260.2 Prototype B 30.4 1.99 6.84 258.8 5.3 264.0 Driver C 31.3 2.04 6.91257.2 3.4 260.3 D 29.4 1.85 6.49 252.1 5.8 257.9 Top Flite A 46.6 1.936.47 176.1 3.1 179.2 Tour ™ B 47.1 2.04 6.45 173.5 2.3 175.7 5 Iron C47.4 2.08 6.51 173.5 1.6 175.1 D 45.6 1.96 6.49 177.1 2.4 179.5

[0207] Note that Ball Type A had results comparable to the other balltypes.

[0208] The foregoing description is, at present, considered to be thepreferred embodiments of the present invention. However, it iscontemplated that various changes and modifications apparent to thoseskilled in the art may be made without departing from the presentinvention. Therefore, the foregoing description is intended to cover allsuch changes and modifications encompassed within the spirit and scopeof the present invention, including all equivalent aspects.

We claim:
 1. A process for forming a golf ball having a plurality ofdeep dimples, said process comprising the steps of: providing anintermediate ball comprising at least a core; providing a moldingapparatus having a generally spherical molding chamber with a moldingsurface defined by (i) a first plurality of raised regions for forming aplurality of dimples on said cover layer, and (ii) a second plurality ofraised regions, each of said second plurality of raised regionsextending beyond said first plurality of raised regions, forconcentrically positioning an object within said molding chamber and forforming deep dimples, and an assembly for administering a flowablematerial into said molding chamber; providing to said molding apparatusa flowable material suitable for use as said cover layer for said golfball; positioning said intermediate ball within said molding chambersuch that said second plurality of raised regions of said moldingsurface contacts and retains said intermediate ball within said moldingchamber; administering said flowable material into said molding chamberand generally between said intermediate ball and said molding surface;and, upon curing, removing the molded ball from said molding apparatus.2. The golf ball produced by the process of claim
 1. 3. The process ofclaim 1, wherein said flowable material comprises an ionomeric material.4. The process of claim 1, wherein said flowable material comprisespolyurethane.
 5. The process of claim 1, wherein said flowable materialcomprises a (i) polymer having an active hydrogen group selected fromthe group consisting of polyol, —OH, amine, —NH₂, and combinationsthereof, and (ii) a polyisocyanate.
 6. The process of claim 1, furthercomprising a step of: adding a barrier coating to said core prior tomolding.
 7. The golf ball produced by the process of claim
 6. 8. Theprocess of claim 1, wherein said step of providing to said moldingapparatus said flowable material is performed by: providing a polyolmaterial to said molding apparatus; providing a polyisocyanate materialto said molding apparatus; and reacting said polyol material and saidpolyisocyanate material to form a polyurethane material.
 9. The processof claim 8, wherein said reacting step is performed in said moldingchamber.
 10. The golf ball produced by the process of claim
 8. 11. Aprocess for forming a cover layer having a plurality of deep dimples ona golf ball core, said process comprising the steps of: providing a golfball core; providing a flowable material adapted for forming said layeron said golf ball core; providing a mold including (i) a generallyspherical molding chamber having an outer surface including a pluralityof raised protrusions that form a plurality of deep dimples in saidlayer, and (ii) provisions for introducing said flowable material intosaid molding chamber; concentrically positioning said golf ball core insaid molding chamber such that said plurality of raised protrusionscontact said golf ball core; and introducing said flowable material intosaid molding chamber whereby said flowable material flows between saidgolf ball core and said outer surface of said molding chamber to therebyform said layer.
 12. The process of claim 11, wherein the height of saidraised protrusions is greater than the thickness of said layer.
 13. Theprocess of claim 11, wherein said flowable material is a polyurethanematerial.
 14. The process of claim 11, wherein said flowable materialincludes (i) a polyol component and (ii) a polyisocyanate component. 15.The process of claim 11, wherein said step of introducing said flowablematerial into said molding chamber includes chemically reacting saidpolyol component with said polyisocyanate component.
 16. The golf ballformed by the process of claim
 11. 17. The process of claim 11, furthercomprising the step of adding a moisture barrier coating to the coreprior to molding.
 18. The golf ball produced by the process of claim 17.19. A process for forming a golf ball having at least one dimple thatextends through an outer layer of said ball, said process comprising:providing an intermediate golf ball assembly comprising at least a core;providing a molding apparatus including a generally spherical moldingchamber having a first population of raised regions for forming aplurality of dimples on an outer layer of said golf ball, and at leastone other raised region having a height that is greater than thethickness of said outer layer; positioning said intermediate golf ballassembly in said molding chamber; and administering a flowable materialadapted to form said outer layer, to said molding apparatus.
 20. Theprocess of claim 19, further comprising a step of hardening saidflowable material to thereby form said outer layer.
 21. The process ofclaim 19, wherein upon positioning said intermediate golf ball assemblyin said molding chamber, said other raised region of said moldingchamber contacts said intermediate golf ball assembly.
 22. The golf ballproduced by the process of claim 19.